Interview: A nose for controversy

By Mick O'Hare

Dubbed “the Emperor of Scent”, biophysicist Luca Turin has stirred up a heated debate about the inner workings of our sense of smell. In the mid-1990s he revived the argument that the human nose detects the presence of a compound from its molecular vibrations rather than its shape, as most researchers believe. He has been busy piecing together evidence to support the vibrational theory, and his latest book, The Secret of Scent, chronicles his quest. Mick O’Hare talks with Turin about which smell convinced him that his theory is correct and what the future might hold for the world of perfumery.

Wasn’t the mystery of smell solved by the time Linda Buck and Richard Axel won the Nobel prize for physiology or medicine in 2004?

Their work was hugely important. Until they discovered human smell receptors the field was a free-for-all and people could come up with any bullshit idea. Their work put a constraint on acceptable theories of how we smell – we are now bound by the fact that the receptors exist. However, the mechanism of how the receptors detect and smell an odour molecule remains a mystery. Buck and others believe it is connected with the shapes of molecules, or specifically parts of their shapes. This theory says two molecules smell the same because they have bits of shape that the receptors perceive to be the same. But which bits? This explains things away rather than actually explaining. It gets you out of a pickle but you cannot use it to predict smells as you can with vibrational theory.

Why is vibrational theory better than shape theory at ...

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